20851801 has 2 divisors, whose sum is σ = 20851802. Its totient is φ = 20851800.

The previous prime is 20851781. The next prime is 20851867. The reversal of 20851801 is 10815802.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19811401 + 1040400 = 4451^2 + 1020^2 .

It is a cyclic number.

It is not a de Polignac number, because 20851801 - 2⁵ = 20851769 is a prime.

It is not a weakly prime, because it can be changed into another prime (20851891) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10425900 + 10425901.

It is an arithmetic number, because the mean of its divisors is an integer number (10425901).

Almost surely, 2^20851801 is an apocalyptic number.

It is an amenable number.

20851801 is a deficient number, since it is larger than the sum of its proper divisors (1).

20851801 is an equidigital number, since it uses as much as digits as its factorization.

20851801 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 640, while the sum is 25.

The square root of 20851801 is about 4566.3772292705. The cubic root of 20851801 is about 275.2418852512.

The spelling of 20851801 in words is "twenty million, eight hundred fifty-one thousand, eight hundred one".